Improve the `get_positional_arg_spans` to take into count the format types

[vincenzopalazzo]

As discussed in #100826 (comment)

Suggested-by @TaKO8Ki

[vincenzopalazzo]

@rustbot claim

[vincenzopalazzo]

@rustbot label +T-compiler +A-diagnostics

[TaKO8Ki]

I think the following are where we need to fix:

rust/compiler/rustc_builtin_macros/src/format.rs

Line 445 in 015a824

has_precision || has_width,

rust/compiler/rustc_builtin_macros/src/format.rs

Line 456 in 015a824

has_precision || has_width,